Apparatus for cleaning strip



Sept. 1, 1942. E. A. MATTESON arm. 2,294,789

APPARATUS FOR CLEANING STRIP Original Filed Oct. so, 1939 2 Sheets-Sheet 1 zillln v 1 INVENTORS & ELW/N A. MATTESO/V BY K/L'L 5. BOWMAN Armelvfnz l 1942- lz. A. MATTESON ETAL, 2,294,789

APPARATUS FOR CLEANING STRIP Original Filed Oct. so. 1939 2 Sheets-Sheet 2 3 NM vn NM wskbt Rtbnx Patented Sept. 1, 1942 UNITED STATES PATENT OFFICE APPARATUS FOR CLEANING STRIP Elwin A. Matteson, Youngstown, and Kiel B. Bowman, Warren, Ohio, assignors to The Aetna Standard Engineering Company, Youngstown, Ohio, a corporation oi Ohio Original application October 30, 1939, Serial No. 301,906. Divided and this application August 29,1941, Serial No. 408,858

3 Claims.

Serial No. 301,906, filed October 30, 1939, now

Patent No. 2,259,260, issued October 14, 1941.

In the cold rolling of strip steel oil is applied to the surfaces of the metal for purposes of lubrication and to prevent oxidization of the surface of the metal. This oil may be either mineral or vegetable, palm oil being commonly used, and its removal after completion of the rolling operation presents a serious problem particularly in connection with strip which is to be used for porcelain enameling or lithograph work. After rolling the strip is usually annealed by heating to a sufficiently high temperature in an annealing furnace. surface of the metal or in the pores of the metal this oil will carbonize during the annealing operation, leaving particles of carbonaceous material in or on the metal. Such particles prevent the proper adherence of lithographic or enamel j coatings andthus the complete removal of all oil from the surfaces of the strip is of great importance.

It has previousl been proposed to pass the strip through an alkali bath. removing a portion of the oil but does not sumciently clean the surface to entirely prevent the formation of carbon particles during annealing. It has also been proposed to scrub the surface of the sheet with an alkali solution but this likewise does not properly remove the oil.

It is among the objects of our invention to provide an improved apparatus for cleaning strip by means of hot alkali solutions whereby oil will be substantially entirely removed and whereby the strip may be passed through the solution at high speed without reducing the cleaning efficiency. Other objects of our invention include the provisions of an improved strip cleaning apparatus which is simple in construction and view, partly in section, of an apparatus for car- If there is any oil on the This results in {I rying out our improved cleaning procedure, the apparatus including'electrical means for heating the strip.

Figure 2 is a diagrammatic side elevational view, partly in section, of a strip cleaning apparatusadapted to carry out the steps of our method but omitting the electrical strip heating equipment.

Figure 3 is a plan view of the apparatusshown in Figure 2.

Referring particularly to Figure 1, a coil of strip 1, which has come from the cold rolling mill and has a coating of oil, is illustrated at the left hand side of the view. This strip passes through the alkali scrubber indicated generally at S and which includes four staggered supporting rolls 2, 3, 4 and 5, and four rotary scrubhing brushes, 8, I, 8 and 9. Adjacent each of the scrubbing brushes is a hot alkali supply pipe The scrubbing brushes and the pipes I9 extend across the entire width of the strip and the pipes are provided with perforations or nozzles adapted to direct a plurality of high velocity jets of hot alkali against the surface of the strip adjacent the scrubbing brushes. As shown by the arrows in Figure 1, the direction of rotation of the scrubbing brushes 6, I, 8 and 9 is preferably opposed to the direction of movement of the strip through the apparatus. It will be understood that suitable feed rolls will be provided to move the strip through the apparatus at the desired rate of speed but such rolls are not shown as they form no part of the present invention.

In the preferred operation of our invention hot alkali solution (for example, soda ash and/or other alkali in water) at a temperature of about 160 F. is discharged upon the strip through the pipes 10. The scrubbing brushes 6, I, 8 and 9, and the hot alkali remove the surface oil from the strip as it passes through the unit S. However, the scrubbing operation usually does not completely remove the oil which has been absorbed into the pores of the metal and in order to remove this oil we pass the strip over a guide pulley ll into the tank 12 containing a hot alkali bath [3. Guide rolls l4 maintain the strip submerged'beneath the surface of the alkali and a roller l5 guides the strip at the exit end of the tank I2. A hood it, having an outlet l1, may be provided to collect and carry away vapors and fumes which arise from the bath l3. In order to maintain the hot alkali bath l3 at the desired temperature, i. e., from about 190 F. to 230 F., heating pipes I8 may be provided in the bottom of the tank l2 and heated by steam or other suitable heating source.

As the cleaning and emulsifying action of the hot alkali on the oil varies approximately as the square of the temperature of the alkali bath, we provide means in the tank i2 for electrically heating the reach of 'strip which is submerged in the bath I3 to a temperature somewhat above the boiling point of the bath, for example, approximately 250 F. This heating of the strip as it passes through the alkali bath l3 causes the solution immediately adjacent the surface of the strip to boil actively and the accompanying heat and agitation materially increase and facilitate the emulsiiication and removal of oil from the pores of the metal.

In order to apply the necessary current to the strip we preferably employ the arrangement shown in Figure 1, although it will be understood by those skilled in the art that various other hook-ups and contact means may be employed. In Figure 1 a central electrode roller [9 engages the strip opposite the central guide roll 14. Suitable means, not shown in detail, are provided for holding the roll [9 in engagement with the strip and electrical connections extend from the roll l9 through the wall of the tank l2, an insulator being indicated at 20, to one terminal of the secondary 2i of the transformer T. The opposite terminal of the secondary 2| is grounded at 22 and electrical connections lead from said opposite end of the secondary to the strip engaging electrode rolls 23 and 24. These rolls are preferably located Opposite the end guide rolls l4 and are held against the strip by any suitable mechanism. Conductors 25 and 26 lead to the secondary 2i of the transformer T and the contact rollers 23 and 24 and their electrical connections are grounded at 21 and 28 respectively.

The transformer T is adapted to reduce the normal line voltage to a low value, for example 6 volts, and sufficient current is applied from the center terminal roller [2 to each of the end terminals 23 and 24 to heat the reaches of the strip indicated at i and l up to approximately 250 F., as explained above.

It will be observed that by means of the scrubber S and the jets of hot alkali solution therein the temperature of the strip may be elevated substantially, for example to about 150 F. This heated strip then enters the bath l2 and its temperature need be raised only a relatively small amount in order to get it up to the preferred value, i. e., the point at which the alkali will boil when in contact with the strip, and thus insure the most effective emulsifying and removal of the oil from the pores of th metal. The scrubber S performs two functions therefore, first to remove the larger portion of the surface film of oil from the strip, and second to preheat the strip so that it may readily be brought up to the desired temperature in the emulsifying bath 13.

The scrubber action alone will remove surface oil but does not effectively remove oil from the pores of the metal. The immersion of a strip in a bath of alkali, without previous scrubbing of the strip, is also ineffective to remove the oil thoroughly because such immersion does not remove the relatively thick' surface oil with sufficient rapidity to permit of practical operation. Our improved procedure in which the strip is first scrubbed and preheated by high velocity hot alkali jets and then passed through an even hotter alkali solution where the alkali has free access to the oil in the pores of the metal with the result that the oil in the pores is emulsifled and floats to the surface of the bath from which it may be skimmed or otherwise removed, results in complete removal of all oil from the metal and the cleaned strip can be annealed and used for enameling or lithographing without trouble.

After passing out of the bath I3 and over the roller 15 the strip is preferably rinsed by means of high pressure water sprays in the rinser R. The water spray nozzles are indicated at 29 and guide rolls 30 direct the strip through the rinser. Immediately following the rinser is a dryer D of any suitable type which evaporates any rinse water remaining on the strip and the oil-free strip will emerge from the dryer ready to be annealed or otherwis processed.

A modified form of our invention is illustrated in Figures 2 and 3, in which the coil of strip 3] 'passes through a scrubber S, substantially low the surface of the alkali bath 4| for a distance sufficient to permit the hot alkali bath to emulsify the oil which remains in the pores of the metal after the scrubbing operation is carried out in the unit S. In this form of our invention the electrical heating of the strip as it passes through the hot alkali bath 4| is not employed as, in some instances and with some types of oil, the additional emulsifying and cleaning action caused by the active boiling of the alkali solution immediately at the surface of the strip may not be required. The washer or rinser R is substantially similar to the rinser R and the dryer D is the equivalent of the dryer D.

The alkali baths [3 and ll may be maintained substantially at the boiling temperature of the solution, i. e., approximately 220 F. by means of superheated steam in the pipes 36 and we have found that the cooperative results of this bath with the combined scrubbing and preheating which occurs in the scrubber S and which removes the surface fllm ofoil in such a manner that the hot bath of alkali in the tank can have access to the oil in the pores of the metal, produces cleaning results impossible to obtain with previously proposed methods and apparatus. Our electrical heating procedure for raising the strip to a temperature higher than the boiling point of the solution permits an agitation and extremely effective release of emulsified oil from the pores of the strip in the bath.

The entire system is adapted for continuous operation and, although we have described in considerable detail the illustrated embodiments of our improved apparatus, it will be understood by those skilled in the art that variations and modifications may be made without departing from the spirit of our invention. We do not, therefore, wish to be limited to the particular form herein described but claim as our invention all embodiments thereof coming within the scope of the appended claims.

We claim:

1. Strip cleaning apparatus of the type described including rctatable scrubbing brushes. means for guiding a strip through said brushes, means for directing high velocity jets of hot alkali solution against the strip adjacent said brushes, a tank having a bath of alkali solution therein, said brushes being disposed ahead of said tank whereby the strip is heated and scrubbed before entering the bath', means for guiding the strip from said scrubbing brushes through said bath, and means for applying heat to the alkal solution in the bath. 2. Strip cleaning apparatus of the type described including a preheater andscrubber having rotatable brushes, means for guiding a strip through said brushes, means for directing high velocity jets of hot alkali against the strip adjacent the brushes, a tank having a bath of alkali solution therein, means for guiding the strip from said scrubber through said bath, means for applying heat to the'alkali solution in the bath, and means for electrically generating heat in only that portion of the strip which is submerged in said bath.

3. Strip cleaning apparatus of the type described including a scrubber having rotatable brushes, means for guiding a strip through said brushes, means for directing high velocity jets of hot alkali against the strip adjacent said brushes, a tank having a bath of alkali solution therein, means for guiding the strip from said scrubber through said bath, means for applying heat to the alkali solution in the bath, and means for causing electric current to flow through only that portion of the strip which is submerged in said bath.

,ELWIN A. MATTESON.

KIEL B. BOWMAN. 

